1. Field of the Invention
The invention relates to a lock for a motor vehicle opening leaf, comprising a wheel intended to be driven in rotation about an axis under the action of an electric motor, said wheel driving in rotation a wrist pin, said wrist pin collaborating with a member for opening said lock so as to move it from a rest position to an open position upon rotation of said motor.
The invention applies more specifically to vehicle tailgate and trunk locks which comprise electric assistance capable of initiating opening of the trunk. These locks generally comprise a lock cylinder intended to take a key and a handle for opening the trunk by hand, and are designed so that when the user unlocks the lock, the electrical assistance also causes the trunk to open. More specifically, these locks generally comprise an intermediate opening member that can be actuated manually when the user actuates the handle, or electrically, for example via a wrist pin set in motion by an electric motor.
2. Description of Related Art
Known from the prior art is a lock of this type in which the wrist pin is secured to a toothed wheel which is driven by the electric motor. The problem with this lock is that in the event of motor failure or a break in the electric power supply occurring during assisted opening, the wrist pin is then immobilized in an intermediate position. This wrist pin consequently jams the opening member in a position for which the trunk is not necessarily open. It is then impossible for the user to open his trunk by operating the handle until the lock has been repaired or until the electrical supply failure has been solved.
The purpose of the invention is to overcome this drawback by proposing a lock which does not prevent the trunk from being opened, even when its electric actuator is immobilized in an intermediate position.
To this end, the subject of the invention is a lock for a motor vehicle opening leaf, comprising a wheel intended to be driven in rotation about an axis under the action of an electric motor, said wheel driving in rotation a wrist pin, said wrist pin collaborating with a member for opening said lock so as to move it from a rest position to an open position upon rotation of said motor, characterized in that said wrist pin is secured to a plate, said plate being mounted so that it can rotate about said axis, and in that it comprises a first and a second associated member for coupling the plate and the wheel in terms of rotation, these members being borne respectively by the wheel and by the plate, said first and second members comprising a drive peg and an associated groove in the form of an arc of a circle so that said wrist pin is free to turn about said axis through a certain angle to prevent said opening member from jamming in the event of failure of said motor.
Such a construction means that in the event of the motor failing in an intermediate position, the wrist pin is still free to rotate through half a turn, so that the opening member has enough mobility for the user to be able to actuate the trunk handle and succeed in opening it.
According to a preferred embodiment of the invention, the lock further comprises a torque limiter connecting in terms of rotation the toothed wheel to said plate, so that said plate positions itself in a stable manner in a neutral position for which said wrist pin is uncoupled from the member in the event of failure of said motor. With this arrangement, the fact of actuating the lock manually when its motor has failed configures this lock in manual mode for which it can be opened and closed manually indefinitely.
According to yet another particular embodiment of the invention in which the torque limiter comprises a spherical stop arranged in said face of said toothed wheel, and a number of spherical holes defining a circle in a corresponding face of said plate, said spherical holes being intended to accommodate said spherical stop. With this arrangement, the torque limiter is included in the plate and the toothed wheel, which makes it possible to reduce the cost of manufacture of the entity.